1. Field of the Invention
The present invention relates to an ac generator for a vehicle such as a passenger car or a truck.
2. Description of the Related Art
As disclosed in JP-A-85402, an ordinary voltage regulator that is mounted in an ac generator for a vehicle has a unitary molded body that includes a circuit board on which an IC chip or transistors are mounted, a heat sink that is fixed to the circuit board by a heat conductive cement and a male connector. In general, the heat sink has a plurality of cooling fins or ribs that extends in a radial direction, as disclosed in JP-A-85402 and JP-P2000-253625A or its counterpart U.S. Pat. No. 6,198,188. Therefore, cooling air is guided by the cooling fins to flow in a radial direction toward the center axis of the ac generator. Because a brush unit of an ordinary ac generator for a vehicle, which has a pair of brushes, is disposed between the voltage regulator and the center axis, the brushes are exposed to the cooling air that has cooled the voltage regulator, or has been heated by the voltage regulator. Therefore, the brushes may be heated by the heated cooling air. In addition, dust or foreign materials may collect around the brush unit. As a result, it is likely that the brushes wear away excessively.